1. Field of the Invention
The present invention relates to an abrasive tape suitably applicable to finishing of surfaces, end faces, and so on of precision components such as optical connector ferrules, semiconductor wafers, metals, ceramics, color filters (for liquid crystal display or the like), plasma displays, optical lenses, substrates of magnetic disk or optical disk, magnetic heads, and optical reading heads, a process for producing it, and a coating agent for abrasive tape.
2. Related Background Art
The precision in grinding for finishing affects the quality of the precision components such as the optical connector ferrules and the semiconductor wafers, and grinding called mechanical polishing has been and is employed for finish grinding.
The mechanical polishing is carried out as follows. First, abrasive particles having particle diameters of 5 to 300 mxcexc are suspended in an alkaline solution such as caustic soda, ammonia, or ethanolamine to prepare an abrasive solution consisting of a colloidal solution of pH 9 to 12. While this abrasive solution is next supplied onto an abrasive cloth comprised of a resin sheet, for example a polyurethane sheet, a precision component such as the optical connector ferrule or the semiconductor wafer is ground on the abrasive cloth.
The above mechanical polishing using the abrasive solution and abrasive cloth has the following problems.
Changes will occur in the concentration of abrasive particles in the abrasive solution during grinding and in the particle size distribution of abrasive particles due to cohesion of abrasive particles, which could result in forming grinding scars or grinding spots on the ground body such as the optical connector ferrule or the semiconductor wafer. The mechanical polishing needs a process for washing the abrasive particles adhering to the surface of the ground body such as the optical connector ferrule or the semiconductor wafer away after completion of grinding, which makes the polishing step complex.
Against it, there is an idea to produce an abrasive tape obtained by applying a coating agent in which the abrasive particles are dispersed in a binder resin solution, onto a base for abrasive tape made of a plastic film and drying it to form an abrasive layer. The optical connector ferrules and semiconductor wafers, etc. are ground on this abrasive tape, but it cannot be used as an abrasive tape for finishing, because it is difficult in producing the abrasive tape to keep the abrasive particles of the particle diameters of 1xcexc less uniformly dispersed in the binder resin solution.
Namely, the high precision grinding for finishing is grinding with fine abrasive particles, but with a decrease in the particle diameters of abrasive particles it becomes difficult to uniformly disperse the fine abrasive particles in the binder because cohesion becomes likely to occur because of an increase in surface energy.
When the abrasive layer is formed from the coating agent containing the abrasive particles in a cohesive state, coarse particles of 5 to 10xcexc are produced in the abrasive layer, which unavoidably form grinding scars on the surface of the ground body.
The present invention has been accomplished under the above circumstances, and an object of the invention is to provide an abrasive tape in which the abrasive particles include no coarse particles in the abrasive layer but include only fine abrasive particles, which can realize precise mirror finishing of precision components such as the end faces of optical connector ferrules and the surfaces of semiconductor wafers, a process for producing it, and a coating agent for abrasive tape.
A first aspect of the present invention is an abrasive tape comprising: a base for abrasive tape; and an abrasive layer formed on the base; wherein the abrasive layer is formed from a coating agent in which abrasive particles of an average particle size in the range of 10 to 100 mxcexc are dispersed in a binder resin solution, with respect to a base for abrasive tape.
A second aspect of the present invention is a process for producing an abrasive tape, comprising the steps of dispersing abrasive particles of an average particle size in the range of 10 to 100 mxcexc in a binder resin solution, producing aggregates of the abrasive particles in the binder resin solution to obtain a coating agent containing the abrasive particles of particle diameters 50 to 800 mxcexc, and applying the coating agent onto a base for abrasive tape.
A third aspect of the present invention is an abrasive tape comprising: a base for abrasive tape; and an abrasive layer formed on the base; wherein the abrasive layer has abrasive particles of an average particle size in the range of 1 to 200 mxcexc and a binder for binding the abrasive particles.
A fourth aspect of the present invention is a coating agent for production of an abrasive tape, comprising an abrasive particle solution containing abrasive particles of an average particle size in the range of 1 to 200 mxcexc and a solvent for abrasive particles, and a binder resin solution containing a binder and a binder solvent.
A fifth aspect of the present invention is a process for producing an abrasive tape, comprising: the steps of preparing a base for abrasive tape; mixing an abrasive particle solution containing abrasive particles of an average particle size in the range of 1 to 200 mxcexc and a solvent for abrasive particles, with a binder resin solution containing a binder and a binder solvent to produce a coating agent; applying the coating agent onto the base for abrasive tape; and drying the coating agent thus applied.
According to the first aspect of the present invention, the abrasive layer is formed by applying the coating agent in which the abrasive particles of the average particle size in the range of 10 to 100 mxcexc are dispersed in the binder resin solution, onto the base for abrasive tape, whereby the abrasive particles in the abrasive layer can be fine particles having small and close particle diameters.
According to the second aspect of the present invention, the abrasive particles of the average particle size in the range of 10 to 100 mxcexc are dispersed in the binder resin solution, thereafter aggregates of the abrasive particles are produced in the binder resin to obtain the coating agent containing the abrasive particles of particle diameters 50 to 800 mxcexc, and then the coating agent is applied onto the base for abrasive tape, whereby the abrasive tape can be obtained with fine particles having small and close particle diameters of the abrasive particles in the abrasive layer.
According to the third aspect of the present invention, the average particle size of the abrasive particles in the abrasive layer formed on the base for abrasive tape can be kept between 1 and 200 mxcexc.
According to the fourth aspect of the present invention, the coating agent containing the abrasive of the average particle size in the range of 1 to 200 mxcexc can be readily obtained.
According to the fifth aspect of the present invention, the abrasive tape having the abrasive layer containing the abrasive of the average particle size in the range of 1 to 200 mxcexc can be produced.